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            <h2 class="title" style="clear: both"><a id="dbset_lk_exclusive"></a>Db::set_lk_exclusive()</h2>
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      <pre class="programlisting">#include &lt;db_cxx.h&gt;
 
int
Db::set_lk_exclusive(int nowait_onoff); </pre>
      <p>
         Configures the database handle to obtain a write lock on the
         entire database when it is opened. This gives the handle 
         exclusive access to the database, because the write lock will block
         all other threads of control for both read and write access.
    </p>
      <p>
        Use this method to improve the throughput performance on your
        database for the thread that is controlling this handle. When
        configured with this method, operations on the database do not
        acquire page locks as they perform read and/or write operations.
        Also, the exclusive lock means that operations performed on the
        database handle will never be blocked waiting for lock due to
        another thread's activities. The application will also be immune to
        deadlocks.
    </p>
      <p>
        On the other hand, use of this method means that you can only 
        have a single thread accessing the database until the handle is
        closed. For some applications, the loss of multiple threads
        concurrently operating on the database will result in 
        performance degradation.
    </p>
      <p>
        Also, use of this method means that you can only have one
        transaction active for the handle at a time.
    </p>
      <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
        <h3 class="title">Note</h3>
        <p>
            This method is incompatible with the 
            <a class="link" href="dbopen.html#open_DB_THREAD">DB_THREAD</a> configuration
            flag.
        </p>
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      <p>
         The <code class="methodname">Db::set_lk_exclusive()</code> method may
         not be called after the 
         <a class="xref" href="dbopen.html" title="Db::open()">Db::open()</a>  method is called.
    </p>
      <p>
         The <code class="methodname">Db::set_lk_exclusive()</code> <span>
            
            <span>
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            </span>
        </span>
    </p>
      <div class="sect2" lang="en" xml:lang="en">
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              <h3 class="title"><a id="lk_exclusive_rep_notes"></a>Replication Notes</h3>
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        <p>
            Replication applications that use exclusive database handles
            need to be written with caution. This is because replication
            clients cannot process updates on an exclusive database until
            all local handles on the database are closed.  Also, attempting
            to open an exclusive database handle on a currently operating
            client will result in the open call failing with the error
            <code class="literal">EINVAL</code>.
        </p>
        <p>
            Also, opening an exclusive database handle on a replication
            master will result in all clients being locked out of the
            database.  On clients, existing handles on the exclusive
            database will return the error
            <code class="literal">DB_REP_DEAD_HANDLE</code> when accessed, and must
            be closed.  New handles opened on the exclusive database will
            block until the master closes its exclusive database handle.
        </p>
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      <div class="sect2" lang="en" xml:lang="en">
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            <div>
              <h3 class="title"><a id="idp5671608"></a>Parameters</h3>
            </div>
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        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp5670320"></a>nowait_onoff</h4>
              </div>
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          <p>
                 If set to <code class="literal">0</code>, this method will block
                 until it can obtain the exclusive lock on the database. If
                 set to some value other than <code class="literal">0</code>, 
                 <code class="literal">DB_LOCK_NOTGRANTED</code> is returned when the
                 handle is opened if the exclusive database lock cannot be
                 immediately obtained.
             </p>
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      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp5667408"></a>Errors</h3>
            </div>
          </div>
        </div>
        <p>
             The <code class="methodname">Db::set_lk_exclusive()</code> <span>
            
            <span>
                method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> 
                exception, encapsulating one of the following non-zero errors, or return one
                of the following non-zero errors:
            </span>
        </span>
        </p>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp5688824"></a>EINVAL</h4>
              </div>
            </div>
          </div>
          <p>
                If the  method was called after 
                <a class="xref" href="dbopen.html" title="Db::open()">Db::open()</a> 
                was called; the method was called on a currently operating
                replication client; or if an invalid flag value or
                parameter was specified.
            </p>
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      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp5673712"></a>Class</h3>
            </div>
          </div>
        </div>
        <p>
                <a class="link" href="db.html" title="Chapter 2.  The Db Handle">Db</a>  
            </p>
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      <div class="sect2" lang="en" xml:lang="en">
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              <h3 class="title"><a id="idp5668848"></a>See Also</h3>
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             <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> 
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